Method and apparatus for heat treating steel articles



May l0, 1927. 1,627,682

l yJ. F. WYZALEK METHOD AND APPARATUS FOR HEAT TREATING STEELARTECLES Fi'led March 14. 192:1

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Patented May 10, 1927.

UNITED -sTATEs PATENT OFFICE.

JOHN F. WYZ'AIE, OF ARLINGTON, NEW JERSEY,v ASSIGNOB TO GENERAL IOTORS g CORPORATION, OF DETROIT, HICHIGAN, AA CORPORATION l' DELAWARE.

METHOD AND APPARATUS FOB HEATTBEATING STEEL ARTICLES.

applicaties ma kann 14, im. seran 10,699,235.

This invention relates to the heat treatment of steel articles and is herein illust trated by reference to a method and aplparatus for heat treating race rings for ro er bearings.

A race ring for a ball or roller bearing must be composed of steel having different properties at different portions of the article. The roller engaging lportion I nust be very hard to resist wear and abrasion but the ring as a whole, `having to .stand Shock and overloads in service and grinding strains in manufacture, must be tough without being brittle. The roller engaging portions of race rings are therefore case hardened while other portions are of low carbon content. As is well known, to refine the grain of a low carbon steel, it must be heated to ahigher temperature than a high carbon steel. If a race ring is heated above the critical ranlgle for the low carbon steel and quenched, t e low carbon portion or .core becomes'lwell refined but the case hardened portion or ment at a temperature above the critical range for the high carbon but not high.

enough to materially affect the already `relined grain of the core.

'An object of this invention is to provide improved hardening apparatus whichl will avoid the expense incident to the'separate handling of the articles for the second heat treatment. v Another object is to provide improved apparatus of this character which will economize heat vby eliminating the first quenching in liquid andthe subsequent reheating of the articles from quenching teinperature. Another object is to simplify the heat treatment and increase production by heat treating articles of varying carbon content as a continuous uninterrupted operation. In accomplishing these and other objects, through one furnace to heat them above the critical'l-range for the low carbon core, then cooled below the critical range for the low carbon. c ore, then, without further cooling or quenching in liquid, are continuously passed through second 'furnaceto heat the case ac uires a coarse grain. This must be removed y another heat treatv the'articles are fed in a Stream, first.

articles above the critical range for the highcgrbon portion, and finally quenched in li uid. y

o these ends and also to improve generall upon devicesy of the character indicate my invention consists'in the various matters hereinafter described and claimed.

Referring tothe drawings, Figure 1 is a side Aelevation of the apparatus partly in section.

Figure 2 is a section von the .line 2-2 of Figure 1. v

Figure 3 is an enlarged view of the connecting tube section between ,theyv furnaces. Figure 4 is' a section on the line 4-4 of Figure 3.

Figure 5 is a section on the line- 5-5 of Figure 6.

Figure 6 connecting tube.

Figure 8 is a side elevation of amodifica'- t1on.

The numeral l() indicates al frame or suport for furnaces'12 and14 which are spaced rom one another in end to' end relation. The furnaces may be identical and are composed of the usual refractory material and ave portsvl through which oil fuel may be admitted. Extending longitudinally through the heating chamber of each furnace are guides 18, herein shown. as tubes through which steel articles are fed in a stream, the tubes protecting the articles from contact with the products of combustion.l Ihe tubes are carried onsup rte 20 of refractory material and have tipo at the bottom to support and guide the articles. lWhen the articles are steel race rings, they engage the flat faces at two points and are less likely to move laterally whilev being fed. Each guide or tube 18 has flanges 24 at the ends, the adjacent Bauges on the tubes of thetwo furnaces being bolted to similar anges26 at the ends of a connecting 'tube 4section 28. VSuitable gaskets 30-of heat insulatinglmaterialare interposed between the connecting flanges and the connecting .ssc-

tion-28 is provided with' a .series of peripheral cooling fins 32 tofacilitate extraction is a vertical section of a jacketed' l" i v 'zo Figure 7 is an end vlew of Figure 6 and` l attened faces22 meeting a temperature above the critical range for the low carbon portions of the articles, then the articles are cooled in the connecting section below the critical range and, without any quenching in liquid, are then carried -through the second furnace which heats them above the critical range for the high carbon portions of the articles but not high enough to materially affect the low carbon portions. Then they are quenched in liquid in the tank 40.

In the ,form of the invention shown in Figures 5 to 7, there are two connecting tubes 42 surrounded by a casing 44 to form a jacket, any suitable fluid such as air or water being admitted at the inlet 46 and discharged at the exit opening 48. i The end walls of the jacketed section have tapped openings 50 to receive screws passing through the flanges on the ends of the furnace tubes.

In Figure 8 there is shown' means for varying'the coolingeffect of the connecting tube fins. Numeral 52 indicates a lower section which is boltednat its ends as before to the ends of the furnace tubes. An upper section 54 normally rests on the lower Sec-l tion but can be raised vertically to allow access of the atmosphere through the 'slots thus formed. Lugs 56 on the lower section receive the threaded portions 58 of hand screws which pass also through lugs 62 on the upper section, there being collars 60 on the screws 58 to support the upper section in different positions of adjustment for varying the size of the slots.

Although the invention has been illustrated by reference to specific steps and apparatus, it should be understood that, in its broader aspects, the invention is not necessarily limited to the' details set forth.

I claim:

1. Apparatus for heat treating steel articles, having, in combination, aiurnace having a tube extending through the heating chamber, 'a second furnace spaced from the first and having a tube extending through the heating chamber, and an unheated tube section joining said furnace tubes; substantially as described.

., 2. Apparatus for heat treating steel artichamber, a second furnace Ispaced from the' first and having a tube extending through the heating chamber, an unheated tube section connecting said furnace tubes, and heat insulating material at the joint between said unheated tube and the furnace tubes; substantially as described.

4. Apparatus for heat treating steel articles, having, in combination, a furnace having tubes extending- .through the heating chamber, a second furnace spaced from the first and having tubes extending through the heating chamber, and a plurality of tube sections joining said furnace tubes, said tube sections being transversely 'connected by flanges forming cooling fins; substantially as described.

- 5. Apparatus for heat treating round articles, having, in. combination, a furnace having a guide extending through the heating chamber, a second furnace spaced from the first and having a guide extending through the heating chamber, a tube section joining said furnace guides, said tube section having attened portions meeting at the bottom to support the articles at two points and guide the same; substantially as del scribed.

6. Apparatus for heat treatin round articles, having, in combination, a rnace having a tube extending through the heating chamber, said tube having flattened ortions meeting at the bottom to support t e articles at two points, and means for pushing the articles through the tube in a stream' substantially as described.

7. Apparatus for heat treating steel articles, having, in combination, a furnace hav'- ing a guide extending through the heating chamber, a second furnace spaced from the first and having a guide extending throu h the heating chamber, and an unheated tu section joining said guides, said' tube section having means to vary the cooling effect; substantially as descrlbed.

8. Apparatus for heat treating steel arti- A cles of highcarbo'n content at one portion and lower carbon content at other portions, having, in combination, a heatin chamber for heating the articles above t e critical range for tne low carbon portion, al chamber for cooling said articles slightly below the critical range, a second heating 'chamcles, having, in combination, a furnace havber for receiving and heating said articles 13o above the critical range for the high-carbon rst and heated to a lower temperature, a portion, and means for quenching said articovered cooling chamber oonnectin said l0 cles; substantiall as described. heating `chambers, and means for eeding 9. Ap aratns or heat treating steel artiarticles through said chambers in a continu- 5 cles of igh carbon content at one.4 portion ous stream; substantiall as dcribed.

and lower carbon content at other portions, lIn testimony whereo I hereunto ax my having, in combination a beati chamber, signature. a Second heating hunter from the JOHN F. WYZALEK. 

